In the testing of materials for use as container walls, reactors in chemical and allied industries and elsewhere using corrosive media, it has been proposed to provide various apparatuses which are intended to render the tests as reproducible as possible.
For example, a test apparatus for the testing of the resistance of enamels to boiling liquids is described in GERMAN INDUSTRIAL STANDARD (DIN) 51157 and comprises a glass cylinder in whose cylindrical wall two fittings are provided for the connection of a reflux condenser and for mounting a thermometer. At both of the ends test specimens can be mounted, with interposition of seals, between triangular plates.
This apparatus has the disadvantage that it does not allow for the stirring or agitation of the corrosive media. A further disadvantage is that with long use sealing problems ensue.
The inability to provide for an extensive agitation of the corrosive medium is a serious disadvantage since only by extensive stirring can a uniform temperature distribution be ensured and it is possible to most effectively use a temperature control device or even do without one if such use is desired.
Furthermore, with the above-mentioned prior device, it is not possible to provide the temperature-sensitive devices, e.g. thermometer, directly in the heated zone of the liquid medium and hence the thermometer is confined only to the vapor space above the medium. Consequently, it is not possible to accurately know the temperature of the medium at the active interface between the corrosive medium and the workpiece specimen.